Method of forming a sheet



y 1965 R. E. GIBSON ETAL I 3, ,8

METHOD OF FORMiNG A SHEET Filed Dec. 22. 1961 RogerE. G i been LeslerWA Meyer IN V EN TORS' BY' AJQMW United States Patent 3,194,866 METHOD OF FORMING A SHEET Roger E. Gibson and Lester W. A. Meyer, Kingsport,

Tenn, assignors to Eastman Kodak Company, Rochester, N.Y., a corporation of New Jersey Filed Dec. 22, 1961, Ser. No. 161,693 3 Claims. (Cl. 264211) 'method for the preparation of sheeting from cellulose esters having improved surface characteristics. Other objects of our invention will appear herein.

We have found that sheets having good surface characteristics may be prepared from cellulose ester compositions by incorporating therein 0.05 to parts, per 100 parts of cellulose ester, of a petroleum oil having a boiling range within 400-935 F extruding the composition through a die to form a sheet, and permitting the emerging sheet to contact a cooling roll positioned so that the sheet travels about 2-5 inches before contacting the cooling roll. The petroleum oil vaporizes from the sheet emerging from the die and condenses on the first cooling roll thereby providing a layer between the roll and the sheet. The thus-formed layer assures obtaining a sheet of good surface characteristics.

Typical cellulose ester extrusion compositions in accordance with our invention are illustrated by the following examples.

Example 1 Parts Cellulose acetate butyrate 100 Dibutyl sebacate 0-40 Bayol 50 l Phenyl salicylate 3 Example 2 Parts Cellulose acetate propionate 100 Dibutyl sebacate 0-40 Bayol F 2 Oil of pennyroyal 0-5 The cellulose acetate propionate has a propionyl range of 43-47%, an acetyl range of 1.5-3.5% and a falling ball viscosity of 20 seconds. Bayol F is a white oil, free of unsaturated components, having a boiling range of 463 930 F. It is available on the market from Esso Standard Oil Company.

Our invention will be further illustrated by the drawing which shows a die 1 provided with a sheet forming orifice 2 which communicates in spaced relationship with a hollow cooling roll 4, provided with suitable cooling means, not shown, and a second cooling roll 5 positioned in axial alignment with the first cooling roll 4. The cooling rolls are mounted on a support, not shown, through shafts 8 and 9, and are provided with suitable means, not shown, for rotation at a controlled rate.

3,194,865 Patented July 13, 1965 The cellulose ester compositions of Examples 1 and 2 were extruded into sheets in the following manner: The cellulose ester composition in flowable condition 6 1s extruded through the orifice 2 of the die 1 and contacts the surface of the first cooling roll 4 at a point 3. The sheet S is passed around the first cooling roll 4, which is revolved at a rate equal to the rate of extrusion, and then around the second cooling roll 5, which is revolved at the same speed as the first cooling roll 4. The sheet S is then wound into a roll or is cut into individual sheets. The temperature of the die 1 is preferably maintained between 370 and 420 F. The temperature of the first cooling roll 4 is advantageously 135-210 F. and the temperature of the second cooling roll 5 is preferably 165-260 F. The first cooling roll 4 is positioned in spaced relationship to the orifice 2 of the die 1 so that the sheet S travels 2 to 5 inches, preferably 2 /2 inches, from the orifice 2 to the point of contact 3 of the first cooling roll 4. During this travel the petroleum oil in the composition first vaporizes and then condenses as at 7 to form a layer or interface between the sheeting S and the first cooling roll 4. The cellulose ester sheeting obtained in accordance with the procedure has a smooth, glossy surface.

Although we prefer to extrude the cellulose ester sheeting onto a cooling roll, other devices may be substituted for the roll without departing from the spirit of our invention. In general, we contemplate the extrusion of cellulose ester sheeting onto any suitable moving surface.

Our invention includes the use of any of the lower fatty acid (i.e., those containing from 2-4 carbon atoms) esters of cellulose. Especially useful products are obtained with the mixed lower fatty acid esters of cellulose, particularly cellulose acetate butyrate.

The petroleum oils which we incorporate in the extrusion compositions of our invention have a boiling range of 400935 F. Especially satisfactory results are obtained with highly refined white oils, free of unsaturated components, which have a boiling range of about 545 F. to 790 F. Petroleum oils in amounts of about 0.05 to 5 parts per parts of cellulose ester produce good results. Preferably, about 1-2 parts of petroleum oil are employed per 100 parts of cellulose ester.

Sheeting prepared in accordance with our invention has a number of useful applications such as packaging. Useful articles may be prepared from the sheeting by vacuum forming, for example.

The invention has been described with reference to certain preferred embodiments, it being understood that variations and modifications can be made within the scope of the invention defined in the following claims.

We claim:

1. A method of forming a sheet having improved surface characteristics from a cellulose ester composition blended with a petroleum oil comprising the steps of extruding into the form of a sheet at a temperature sufiicient to vaporize the petroleum oil a composition comprising (a) 100 parts by weight of a compound selected from the group consisting of the lower fatty acid esters of cellulose and the mixed lower fatty acid esters of cellulose and,

(b) 0.05 to 5 parts by weight of a petroleum oil having a boiling point within the range of 400 F. to 935 F moving the emerging sheet through a distance of about (a) 100 parts of a cellulose acetate butyrate and 2,201,747 (b) 1-2 parts of petroleum oil having a boiling point 2,364,435 within the range of 545 F. to 790 F. 2,412,920

3. A method according-to claim 2 wherein the corn- 2,499,526 position comprises 5 2,559,794 (a) 100 parts of cellulose acetate propionate and 6,0 (b) 1-2 parts of a petroleum oil having a boiling point 2,909,

within the range of 545 F. to 790 F.

References Citefl by the Examiner UNITED STATES PATENTS 2,027,829 1/36 Kratz 264-213 Staudt 264217 Foster et a1 264-210 Soday 106-191 Prichard 106--191 Prichard 264217 Chren et al.

Jensch.

ROBERT F. WHITE, Primary Examiner.

10 MICHAEL V. BRINDISI, ALEXANDER H. BROD- MERKEL, Examiners. 

1. A METHOD OF FORMING A SHEET HAVING IMPROVED SURFACE CHARACTERISTICS FROM A CELLULOSE ESTER COMPOSITION BLENDED WITH A PETROLEUM OIL COMPRISING THE STEPS OF EXTRUDING INTO THE FORM OF A SHEET AT A TEMPERATURE SUFFICIENT TO VAPORIZE THE PETROLEUM OIL A COMPOSITION COMPRISING (A) 100 PARTS BY WEIGHT OF A COMPOUND SELECTED FROM THE GROUP CONSISTING OF THE LOWER FATTY ACID ESTERS OF CELLULOSE AND THE MIXED LOWER FATTY ACID ESTERS OF CELLULOSE AND, (B) 0.05 TO 5 PARTS BY WEIGHT OF A PETROLEUM OIL HAVING A BOILING POINT WITHIN THE RANGE OF 400* F. TO 935* F. MOVING THE EMERGING SHEET THROUGH A DISTANCE OF ABOUT 2-5 INCHED TO A COOLED MOVING SURFACE WHILE CONDENSING THE VAPORIZED PETROLEUM OIL ON THE COOLED MOVING SURFACE CLOSELY ADJACENT THE SURFACE OF THE SHEET AND FORMING A LIQUID INTERFACE BETWEEN THE SHEET AND THE COOLED MOVING SURFACE. 